Question 1

Can two Rh-positive parents have an Rh-negative child?

Accepted Answer

Yes. If both parents are heterozygous carriers (Dd) of the recessive Rh-negative allele, there is a 25% mathematical probability that their child will inherit two copies of the d allele (dd) and be Rh-negative.

Question 2

Can an AB parent have an O blood type child?

Accepted Answer

Under standard Mendelian inheritance, no. An AB parent contributes either an A or B allele to every gamete. A child requires two recessive O alleles (ii) to express Type O blood.

Question 3

What is Rh incompatibility risk during pregnancy?

Accepted Answer

Rh incompatibility occurs when an Rh-negative mother carries an Rh-positive fetus. If fetal red cells enter maternal circulation, the mother can develop anti-D antibodies that attack fetal red blood cells in subsequent pregnancies, preventable via RhoGAM prophylaxis.

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